For vehicles with diesel engines, it has always been advantageous to preheat the cold fuel coming from the fuel tank before its introduction to the injection pump. Two reasons for warming up the fuel are that first, cold fuel is more viscous and tends to produce more horsepower. This extra horsepower becomes detrimental to the components of an engine when it exceeds the rate capacity of the engine. Secondly, a more noticeable problem is that with cold fuel, the operator experiences an increase in horsepower from his vehicle. As the fuel warms up as the vehicle is operated, the operator experiences a decrease in horsepower. Since this decrease in power is gradual, the operator tends to believe it is due to some malfunctioning of his equipment.
In order to warm up the fuel, various vehicle manufacturers have tried several different approaches. One system includes the use of using the water jacket of the engine to preheat the fuel. Once the water is heated by the combustion in the cylinders, the heat is transferred, such as by a heat exchanger, to warm up the fuel. A second approach uses a separate heater to preheat the fuel. A third solution is taught in U.S. Pat. No. 3,768,454, issued to Markland in Oct. 1973, entitled "Fuel Heater". This patent teaches the use of a fuel tank with a confined mixing zone and the use of a temperature sensitive proportional valve means. The valve is responsive only to the temperature of the fuel at the inlet of the feed line for dividing the flow of the fluid from the return line to the first and second inlets of the fuel tank means. By re-routing and mixing the fuel within the fuel tank, Markland is able to heat up the incoming fuel. A fourth solution appears in U.S. Pat. No. 2,881,828, issued to McGinnis in April 1959, entitled "Apparatus for Controlling the Operating Temperature of a Diesel Motor Fuel System Fluid". This patent teaches the use of a temperature sensitive thermostat in conjunction with a heat exchanger. In this system, warm unused fuel from the injection pump is circulated about a coiled fuel supply line to heat up the incoming fuel. If additional heat is needed, the warm fuel is then intermixed with the incoming cold fuel. These and other attempts to solve the problem of warming up the incoming fuel have not totally resolved the problem mainly because of their inability to quickly and effectively transfer the desired amound of heat to the incoming fuel. The present invention solves this troublesome problem by providing an improved fuel temperature control system.
The general object of this invention is to provide an improved fuel temperature control system for a vehicle. A more specific object of this invention is to provide a fuel temperature control system for attachment to a vehicle having a diesel engine.
Another object of this invention is to provide a fuel temperature control system which is capable of quickly bringing the cold incoming fuel up to a predetermined temperature value.
Still another object of this invention is to provide an inexpensive fuel temperature control system for diesel engines.
A further object of this invention is to provide a fuel temperature control system which will quickly supply a source of heat to the cold incoming fuel.
Other objects and advantages of this invention will become more apparent from a reading of the following description and the drawings.